Antenna Switching Arrangement

ABSTRACT

An antenna arrangement comprising an input/output connection and a first and a second tuning network with different transfer functions. The arrangement additionally comprises an antenna and a switch for connecting the input/output connection of the arrangement to one of said tuning networks, with a second switch for connecting the antenna of the arrangement to the tuning network to which the input/output connection of the arrangement has been connected. The arrangement comprises a sensor for sensing a form factor of the arrangement or of an apparatus in which the arrangement is used, and said sensor can be used for influencing said first and second switches, so that a device which has been connected to the arrangement may be connected to the antenna via a tuning network optimal for the current form factor of the arrangement.

TECHNICAL FIELD

The present invention discloses an antenna arrangement for thetransmission and/or reception of electromagnetic signals. Thearrangement comprises input/output means, and at least a first and asecond tuning network with different transfer functions. The arrangementalso comprises a first antenna and a first switch for connecting theinput/output means of the device to one of the tuning networks. Thearrangement also has a second switch for connecting the antenna of thearrangement to the tuning network to which the input/output means of thedevice have been connected.

BACKGROUND

The performance of an antenna used for the reception and/or transmissionof electromagnetic signals is influenced by, inter alia, the immediateenvironment surrounding the antenna, due to electromagnetic interactionbetween the antenna and objects proximate to the antenna. Theantenna-object interaction can manifest itself in undesirable ways, forexample in the form of high return loss, decreased radiation efficiency,and radiation pattern perturbations. By designing the antennaarrangement in a proper way, taking into account the influence of thesurrounding environment, it is possible to tune the performance of theantenna for the specific environment in which the antenna is used.

Antennas which are used in devices or terminals such as, for example,cell phones or portable computers, are however, exposed to a changingenvironment, such as, for example, the configuration of a “clam shell”cellular phone, or the body/lid configuration in the case of a portable“notebook” computer. In such changing environments, an antenna cannot betuned once and for all for optimal performance. Instead, there is a needfor solutions which can adaptively tune the antenna's performancedepending on the situation, since there is no single tuning thatmaximizes the antenna's, and the corresponding communications system'sperformance for all possible environments.

A solution which may adapt an antenna or an antenna arrangement to anumber of environment scenarios can offer good antenna performance forterminals used for mobile communications, due to the nature of usage ofsuch devices. In particular, notebook (“laptop”) computers are typicallyused in one of only three basic ways:

-   -   lid open, i.e., notebook display visible and keyboard available;    -   lid closed, i.e., notebook display not visible;    -   lid closed (or non-existent), and display facing away from the        computer chassis, such as in a computer using a “touch screen        user interface”.

The second of these is typical of the stationary scenario, when acomputer is connected to a “docking station” or “port replicator”,whereas the first and third are typical of an “unconnected scenario”.When the main influence on the antenna performance is the laptopcomputer configuration, i.e., the lid position in relation to thecomputer chassis, as is almost always the case, an adaptive solution toa variable environment can be limited to handle a finite set ofscenarios, in this case two. This allows for a low-complexity, low-costsolution, for example implemented as configuration-based signal routingusing switched networks.

A communications system in which an antenna or antenna arrangement isinstalled will only achieve the desired performance level if the antennaperformance, for example in terms of efficiency, pattern correlation (inthe case of multiple antennas and for a given propagation channel), ordirectionality (radiation pattern spatial selectivity), is maintained.Since the antenna performance will be highly affected by theinstallation scenario, it is crucial to account for the properties ofthe platform (notebook, PDA, handset, etc.) when choosing the antennasolution. Some platforms, such as notebook computers with lids andclamshell phones, have inherently variable form factors, i.e. physicalshapes, which makes choosing an antenna solution difficult. Differentmodes of operation (for example ‘lid open’ or ‘lid closed’) may requiresignificantly different antenna solutions in order to provide goodantenna performance.

Most existing antenna designs for portable devices ignore the problem ofa variable form factor in the portable device. One and the sameantenna(s) is/are used, regardless of the current configuration of thedevice in which the antenna(s) is/are installed, in addition to whichthe antennas are designed for a certain mode of operation, or aredesigned to provide an average performance quality which allows thedevice in which the antenna is installed to operate with an acceptabledegree of performance for all form factors of the device. Thus, theantenna performance, and hence the corresponding communications system'sperformance, will never be ideal for all scenarios.

There are known solutions which do account for different form factors,and which are based on tuning the antenna performance based on some sortof quality measurement. One example of such a solution is shown in USpatent application 2004/0027300 A1, Young-Eil Kim et al.

The solution disclosed in US 2004/0027300 A1 teaches the use of a switchinstalled in a laptop computer, by means of which it is possible tosense if the lid of the laptop is open or closed, and to switch betweendifferent antennas based on this.

It would be desirable to improve the solution shown in US 2004/0027300A1, so that an increased tuneability and thereby improved antenna andcommunications system performance can be obtained.

SUMMARY

Thus, as stated above, there is a need for a solution by means of whichan increased tuneability in an antenna arrangement can be obtained, sothat the antenna arrangement may be adapted to changing form factors ofa device in which it is used, or in the antenna arrangement as such.

This need is addressed by the present invention in that it discloses anantenna arrangement for the transmission and/or reception ofelectromagnetic signals. The arrangement of the invention comprisesfirst input/output connection and at least a first and a second tuningnetwork, which have different transfer functions.

Each of the tuning networks of the arrangement also comprise a first anda second input/output port, and the arrangement additionally comprises afirst antenna and a first switch for connecting the first input/outputconnection of the arrangement to the first input/output port of one ofsaid tuning networks. There is also a second switch for connecting theantenna of the arrangement to the second input/output port of the tuningnetwork to which the input/output connection of the arrangement has beenconnected.

The inventive arrangement comprises a sensor for sensing a form factorof the arrangement or of an apparatus in which the arrangement is used,and this sensor can be used for influencing the first and secondswitches of the arrangement, so that a device which has been connectedto the arrangement may be connected to the antenna of the arrangementvia a tuning network which is optimal for the current form factor of thearrangement or of an apparatus in which the arrangement is used.

Thus, by means of the present invention, increased tuneability of anantenna arrangement based on form factor is obtained.

The invention also discloses a method for use in an antenna arrangement.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention will be described in more detail in the following, withreference to the appended drawings, in which

FIGS. 1-5 show different embodiments of the invention, and

FIG. 6 shows a flow chart of a method of the invention.

DETAILED DESCRIPTION

FIG. 1 shows a first embodiment of an arrangement 100 of the invention.As is indicated, the arrangement 100 comprises a first input/outputconnection 110, as well as comprising at least a first 130 and a second150 tuning network. Suitably but not necessarily, the two tuningnetworks 130, 150, have different transfer functions.

The arrangement 100 also comprises a first antenna 160, which may beused for the transmission and/or reception of electromagnetic signals toand/or from a device which has been connected to the arrangement via theinput/output 110.

As is indicated in FIG. 1, each of the tuning networks 130, 150, alsocomprises a first and a second input/output port, 125,145/135,155. Inaddition, the arrangement 100 comprises a first switch 115, which mayconnect the input/output connection 110 of the arrangement to one of thetuning networks 130, 150, via the inputs/outputs 125, 145 of the tuningnetworks.

In addition, the arrangement comprises a second switch 140, which may beused to connect the antenna 160 of the arrangement to the secondinput/output port of one the tuning networks 130, 150, so that anexternal device which has been connected to the arrangement 100 via theinput/output 110 may be connected to the antenna 160 via one of thetuning networks 130, 150. The switches can be of any suitable type, suchas pin-diode switches or electromechanical switches, including MEMS(micro electro mechanical system) switches.

As has been mentioned previously in this text, one of the goals of thepresent invention is to obtain an antenna or antenna arrangement whichhas a higher degree of tuneability than previous suchantennas/arrangements, the tuneability being with respect to a formfactor of the antenna arrangement or a device in which the antennaarrangement is installed.

In order to achieve this, the device 100 is provided with a sensor 120for sensing at least a first form factor of the antenna arrangement or adevice in which the antenna arrangement is installed. The form factor(s)can be of a wide variety, but mention can especially be made of suchform factors as the angle of a movable or rotatable part of a foldabledevice, e.g. clam shell cellular phones or laptop computers, or deviceswhich have retractable parts, as is the case with some PDAs (PersonalDigital Assistants) and certain kinds of cellular phones.

In the cases enumerated above, i.e. foldable/retractable devices, thesensor 120 will thus be able to sense one of a number ofangles/positions, or can be continuous, i.e. it senses the presentangle/position of the device, instead of sensing one of a number ofpre-programmed angles/positions of the device. Such angle/positionsensors can be designed according to a number of principles, which areknown as such, and the sensor will thus not be described in more detailhere. However, if the form factor which is to be sensed is the positionof a movable/retractable/rotatable part of a device, examples of sensorsare:

-   -   Mechanical sensors, such as spring loaded plungers    -   Magnetic sensors,    -   Optical sensors.

However, the form factor which is sensed by the sensor may be one of alarge number of form factors, especially if the term “form factor” isinterpreted in the broad sense in which it is used by the presentdisclosure. For example, the sensor could sense the SWR, the StandingWave Ratio, of the transmitted signal, or it could sense the impedanceof the arrangement or the device in which the arrangement is used, sincethe impedance may change if the arrangement or device is touched by oris proximate to an external body, such as that of, for example, a humanuser, and the impedance change may depend on the force with which thedevice/arrangement is touched as well as on which parts of thedevice/arrangement that is exposed to the external body and the locationof the external body relative to the device/arrangement.

Thus, the sensor 120 will output a signal which depends on one or moreform factors. This signal is used as input to the first and secondswitches 115, 140 of the antenna arrangement 100, which is alsoindicated in FIG. 1. Consequently, the switches 115, 140, may use theinput from the sensor 120 in order to connect the input 110 of thearrangement to one of the tuning networks 130, 150, and to connect thetuning network to which the input is connected to the antenna 160 of thearrangement. Thus, a device which has been connected to the arrangementvia the input/output connection 110 may be connected to the antenna 160via the tuning network 130, 150 which is optimal for the present formfactor, as sensed by the sensor 120.

As mentioned previously, the first 130 and the second tuning networks150 preferably have different transfer functions. The transfer functionsmay differ for example due to different impedances of the tuningnetworks. Thus, in the example with different impedances, a device whichhas been connected to the arrangement 100 will be connected to theantenna 160 via a tuning network which has an impedance which issuitable for the in situ antenna impedance caused by the present formfactor of the arrangement 100. In the case of laptop computers forexample, the in situ antenna impedance will vary with the angle betweenthe foldable lid and the body of the computer.

FIG. 2 shows a second embodiment 200 of the arrangement of theinvention. Components which are similar to those of the embodiment 100shown in FIG. 1 have retained their reference numerals in FIG. 2. As canbe seen from FIG. 2, a major difference between the embodiment 200 andthe embodiment 100 of FIG. 1 is that the embodiment 200 comprises asecond antenna 260, and that the second switch 140 may be used toconnect the output of one of the tuning networks to one of the twoantennas. Thus, an external device which has been connected to thearrangement 100 may be connected to an antenna 160, 260 which is optimalfor the current form factor sensed by the sensor 120 via a tuningnetwork which is optimal for the current form factor.

A third embodiment 300 of the invention is shown in FIG. 3. Thisembodiment is a more general form of the embodiments shown in FIGS. 1and 2, and comprises M tuning networks and N antennas, where N≧2 andM≧N. Thus, by means of the first 115 and second 140 switches, anexternal device which has been connected to the arrangement 300 may beconnected to an antenna 160, 260, 360 which is optimal for the currentform factor sensed by the sensor 120 via a tuning network 130, 150, 350which is optimal for the current form factor, where the embodiment 300offers a larger number of antennas and tuning networks than available inthe embodiments 100 and 200.

FIG. 4 shows a fourth embodiment 400 of the invention. This embodimentis similar to the one shown in FIG. 3, but has a plurality K ofinput/output connections, where K≧2. The general function of thearrangement 400 is the same as the one of the arrangement 300 of FIG. 3,with the difference, however, that the first 115 and second switch 140may be used to connect an input 1-K to an antenna 1-N via a tuningnetwork 1-M in a way which is optimal for the current form factor of thearrangement 400 as sensed by the sensor 120.

Finally, FIG. 5 shows an embodiment 500 of the invention. Thisembodiment 500 comprises a feature which may be used in any of the otherembodiments described in this disclosure: the output of the sensor 120may also be used for influencing at least one of the tuning networkscomprised in the arrangement, so that the tuning network is adapted to aform factor of the arrangement or of an apparatus in which thearrangement is used, as sensed by the sensor 120.

As an example, in the case where the transfer functions of the tuningnetworks differ due to different impedances, it could be conceivable tohave at least one tuning network with variable impedance, which could bevaried according to the input from the sensor 120. Thus, in one possibleembodiment with variable tuning networks, each network could be variedwithin a certain impedance range.

FIG. 6 shows a rough flow chart of a method of the invention. Stepswhich are options or alternatives are shown in dashed lines. Referencenumbers of components below are taken from FIGS. 1-5.

Thus, the method 600 of the invention may be used in an antennaarrangement such as those shown in FIGS. 1-5, which are used for thetransmission and/or reception of electromagnetic signals. According tothe method, as indicated in step 610, the arrangement is equipped withthe following:

-   -   a first input/output connection, 110 and,    -   at least a first, 130, and a second, 150 tuning network, which        tuning networks have different transfer functions,    -   each of said tuning network also comprising a first 125,145, and        a second, 135,155, input/output port,    -   a first antenna 160,    -   a first switch 115 for connecting the first input/output        connection of the arrangement to the first input/output port of        one of said tuning networks, and    -   a second switch 140 for connecting the antenna of the        arrangement to the second input/output port of the tuning        network to which the input/output connection of the arrangement        has been connected.

Step 615 shows that the method comprises the use of a form factor of thearrangement or of an apparatus in which the arrangement is used forinfluencing, step 620, said first, 115, and second, 140, switches, sothat a device which has been connected to the arrangement may beconnected, step 625, to the antenna via a tuning network which isoptimal for the current form factor of the arrangement.

As indicated in step 630, the method may additionally comprise the useof a second antenna 260 in the arrangement, and also using said secondswitch 140 for connecting one of the antennas, 160, 260, of thearrangement to the second input/output port of the tuning network towhich the input/output connection of the arrangement has been connected,so that a device which has been connected to the arrangement may beconnected to an antenna which is optimal for the current form factor ofthe arrangement via a tuning network which is optimal for the currentform factor of the arrangement.

Step 635 indicates that the method of the invention may additionallycomprise the use in the arrangement of M tuning arrangements, M>2, and Nantennas, N>2, with M≧N, and letting the first and second switches ofthe arrangement be used to connect a device which has been connected tothe arrangement to an antenna which is optimal for the current formfactor of the arrangement via a tuning network which is optimal for thecurrent form factor of the arrangement.

As shown in step 640, the method may comprise the use of at least asecond input/output connection to the arrangement, and the use of thefirst switch 115 for connecting one of the input connections of thearrangement to one of the tuning networks.

According to the inventive method, the first switch may be used toconnect one of the input connections of the arrangement to one of saidtuning networks based on said form factor.

As shown in step 645, the method 600 may comprise the use of the formfactor for influencing at least one of the tuning networks, so that saidat least one tuning network is adapted to a form factor of thearrangement or of an apparatus in which the arrangement is used.

The invention is not limited to the examples of embodiments describedabove and shown in the drawings, but may be freely varied within thescope of the appended claims. It should be noted, for example, that themultiple antennas employed in an antenna arrangement of the invention donot need to be physically separate antennas, but may be separate antennafunctions in one and the same physical unit. The same is true for themultiple tuning networks used in an antenna arrangement of theinvention, i.e. they do not need to be physically separate tuningnetworks, but may be separate tuning network functions in one and thesame physical unit.

Also, the tuning networks may be tuneable with respect to one or morefactors other than impedance. For example, tuning networks for use inthe invention could have different and tuneable filter functions.

Also, the sensor used in the invention may gauge and provide multiplesimultaneous form factor values, which may be used individually tocontrol switches and tuning networks or may be combined to provide oneor more derived form factor values for controlling switches and tuningnetworks.

1. An antenna arrangement for transmission and/or reception ofelectromagnetic signals, the arrangement comprising a first input/outputconnection and at least a first and a second tuning network, whichtuning networks have different transfer functions, each of said tuningnetwork also comprising a first and a second input/output port, thearrangement additionally comprising a first antenna and a first switchfor connecting the first input/output connection of the arrangement tothe first input/output port of one of said tuning networks, with asecond switch for connecting the antenna of the arrangement to thesecond input/output port of the tuning network to which the input/outputconnection of the arrangement has been connected, the arrangement beingcharacterized in that it comprises a sensor for sensing a form factor ofthe arrangement or of an apparatus in which the arrangement is used, andin that said sensor can be used for influencing said first and secondswitches, so that a device which has been connected to the arrangementmay be connected to the antenna via a tuning network which is optimalfor the current form factor of the arrangement.
 2. The arrangement ofclaim 1, additionally comprising a second antenna, in which arrangementsaid second switch can also be used for connecting one of the antennasof the arrangement to the second input/output port of the tuning networkto which the input/output connection of the arrangement have beenconnected, so that a device which has been connected to the arrangementmay be connected to an antenna which is optimal for the current formfactor of the arrangement via a tuning network which is optimal for thecurrent form factor of the arrangement.
 3. The arrangement of claim 1,additionally comprising M tuning networks, M>2, and also comprising Nantennas, N>2 and M≧N, in which arrangement the first and secondswitches can be used to connect a device which has been connected to thearrangement to an antenna which is optimal for the current form factorof the arrangement via a tuning network which is optimal for the currentform factor of the arrangement.
 4. The arrangement of claim 1,additionally comprising at least a second input/output connection, inwhich arrangement said first switch may also be used to connect one ofthe input connections of the arrangement to one of said tuning networks.5. The arrangement of claim 4, in which the first switch connects one ofthe input connections of the arrangement to one of said tuning networksbased on the output of said sensor for sensing a form factor.
 6. Thearrangement of claim 1, in which said sensor is also used forinfluencing at least one of said tuning networks, so that said tuningnetwork is adapted to a form factor of the arrangement or of anapparatus in which the arrangement is used.
 7. A method for use in anantenna arrangement for transmission and/or reception of electromagneticsignals, the method comprising equipping said arrangement with a firstinput/output connection and, at least a first and a second tuningnetwork, which tuning networks have different transfer functions, eachof said tuning network also comprising a first and a second input/outputport, a first antenna and a first switch for connecting the firstinput/output connection of the arrangement to the first input/outputport of one of said tuning networks, • a second switch for connectingthe antenna of the arrangement to the second input/output port of thetuning network to which the input/output connection of the arrangementhas been connected, the method being characterized in that it comprisesthe use of a form factor of the arrangement or of an apparatus in whichthe arrangement is used for influencing said first and second switches,so that a device which has been connected to the arrangement may beconnected to the antenna via a tuning network which is optimal for thecurrent form factor of the arrangement.
 8. The method of claim 7,additionally comprising the use of a second antenna in the arrangement,and also using said second switch for connecting one of the antennas ofthe arrangement to the second input/output port of the tuning network towhich the input/output connection of the arrangement has been connected,so that a device which has been connected to the arrangement may beconnected to an antenna which is optimal for the current form factor ofthe arrangement via a tuning network which is optimal for the currentform factor of the arrangement.
 9. The method of claim 7, additionallycomprising the use in said arrangement of M tuning arrangements, M>2,and N antennas, N>2 and M≧N, according to which method the first andsecond switches of the arrangement may be used to connect a device whichhas been connected to the arrangement to an antenna which is optimal forthe current form factor of the arrangement via a tuning network which isoptimal for the current form factor of the arrangement
 10. The method ofclaim 7, comprising the use of at least a second input/output connectionto the arrangement, and also using said first switch for connecting oneof the input connections of the arrangement to one of said tuningnetworks.
 11. The method of claim 10, according to which the firstswitch is used to connect one of the input connections of thearrangement to one of said tuning networks based on said form factor.12. The method of claim 7, comprising the use of said form factor forinfluencing at least one of said tuning networks, so that said at leastone tuning network is adapted to a form factor of the arrangement or ofan apparatus in which the arrangement is used.